Article comprising light absorbent composition to mask visual haze and related method

ABSTRACT

A transparent article includes a continuous polyester matrix having at least one incompatible filler dispersed therein. The incompatible filler provides domains in the polyester matrix, each domain having a particular dimension, thus providing a range of dimensions for the domains in the article. To create haze, the dimensions are within the range of from about 380 nm to about 720 nm. Once the range of dimensions is determined, a light absorbent composition can be found which absorbs light at a range of wavelengths that at least substantially covers the range of dimensions of the domains. In doing so, it has been found that the haze of the article can be substantially masked. Method for producing the article and for masking the haze are also provided.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.13/340,936 filed on Dec. 30, 2011, now abandoned, which is acontinuation of U.S. patent application Ser. No. 12/823,447 filed onJun. 25, 2010 and is now granted U.S. Pat. No. 8,057,874 which is acontinuation of U.S. patent application Ser. No. 10/769,167 filed onJan. 30, 2004 and is now granted U.S. Pat. No. 7,833,595 and claims thebenefit of U.S. Provisional Application Ser. No. 60/444,313, filed onJan. 31, 2003. The teachings of all of which are incorporated in theirentirety. Other related applications are application Ser. No.11/618,437, which is a divisional of Ser. No. 10/769,167 and is nowgranted U.S. Pat. No. 8,052,915; application Ser. No. 11/617,248, whichis a continuation of Ser. No. 10/769,167 and is now granted U.S. Pat.No. 7,438,960; application Ser. No. 12/823,306, which is a continuationof Ser. No. 10/769,167 and is now granted U.S. Pat. No. 8,053,050;application Ser. No. 12/823,422, which is a continuation of Ser. No.10/769,167 and is now granted U.S. Pat. No. 8,067,074; and applicationSer. No. 12/823,486, which is a continuation of Ser. No. 10/769,167 andis now granted U.S. Pat. No. 8,057,874.

BACKGROUND OF THE INVENTION

This invention relates to the production of a transparent article and,more particularly, to the production of a shaped, transparentthermoplastic article, such as a container or bottle, having anincompatible filler, preferably a gas barrier strengthening fillerdispersed therein, wherein the light absorption of the article has beenaltered to effectively mask or reduce the visual haze of the article.

Thermoplastic polymers, such as polyesters, have long been used in theproduction of packaging materials, including preforms which are thenblown or otherwise oriented into a desired form as necessary for theproduction of plastic articles such as containers and/or bottles forfood and beverage storage and delivery. Among the most preferred andcost-effective thermoplastic polymers used for this purpose arepoly(ethylene phthalate) resins. Poly(ethylene terephthalate) (PET), aswell as other polyesters, when processed properly under the rightconditions and oriented into a desired shape, provides a high clarity,low haze article. Consequently, the plastic bottling industry has usedPET and similar polyesters for several years in its production ofplastic containers and bottles for food and beverages.

Unfortunately, while plastic containers made from polyester, provideexcellent high strength containers having excellent gas barrierproperties for most foods and beverages, they are presently not suitableas beer containers or other food containers where extremely low gaspermeability is required. It will be appreciated that when oxygen andother air gases come into contact with certain foods and beverages, suchas beer for example, the beer oxidizes or otherwise becomes stale.Consequently, attempts have been made heretofore to reduce theoxygen/gas permeability of the container or, stated another way, toincrease the gas barrier strength of the container.

One known way to reduce oxygen/gas permeability or to increase the gasbarrier strength of the container is to blend certain gas barrierstrengthening fillers with the polyester in the container. For instance,certain polyamides, such as polyxylylene amides, are well known in theart to provide improved gas barrier strength to polyester containers. Toproduce these containers, the filler is typically blended or dispersedin the polyester by processes known in the art and then the article ismanufactured. In some instances, the containers may be molded as byinjection molding and the like. In other instances, preforms of thecontainers are prepared such as by injection molding or extrusion, andare then blown or otherwise oriented into the desired size and shape.

Various patents and patent publications have taught the use ofpolyester/polyamide blend compositions for forming an article having lowhaze and reduced gas permeability compared to polyester alone. In atleast one patent publication, in order to provide a low haze/low gaspermeability container, it is stated that the blend composition employ apolyamide having a number average molecular weight of less than 15,000.That patent publication further makes it clear that blends of highermolecular weight polyamides with polyester are known to have high hazevalues which limit their practical use in the food and beveragecontainer industry.

In other words, heretofore, few, if any, blends of polyester and thesegas barrier strengthening fillers, such as higher molecular weightpolyamides, have been used in the plastic container or bottlingindustry, or any industry where transparent, high clarity articles aredesired, because it is a well-known fact that, upon orienting orstretching an article containing a blend of polyester and polyamide, thearticle loses much of its clarity and transparency, i.e., becomesvisually cloudy or hazy. This characteristic is known in the industry ashaze.

Haze, as described in most of the patent literature, can be measured,much like any other physical property. Measurements to determine thelevel or amount of haze may be obtained using a colorimeter (e.g.,Hunter Lab Color Quest) and following ASTM D1003. Haze is typicallyreported as a percentage based upon the thickness of the article and canbe calculated by the equation

${{Haze}\mspace{14mu}\%} = {\frac{T_{Diffuse}}{T_{Total}} \times 100}$where Haze % equals transmittance haze, T_(Diffuse) equals diffuse lighttransmittance, and T_(Total) equals total light transmittance. A 4% hazemeasurement in a container sidewall approximately 15 mils thick isnormally visible to the naked eye. Generally, when testing containersmade from different blends of polyester and polyamides, haze values havebeen measured in the 15% to 35% range for these 15 mil thick containers.For purposes of this invention, this type of haze will often be referredto hereinafter as “physical haze” or “measured haze.”

Moreover, as the amount of gas barrier strengthening filler used in thepolyester/filler blend increases, the physical haze value alsoincreases. In fact, it has been found by others that effective blendratios of polyester (e.g., PET) and aromatic polyamides (e.g.,poly(m-xylylene adipamide) commonly referred to as MXD6) provide forphysical haze values in the 20% to 30% range upon orienting the polymersinto the form of a container again having a wall thickness of about 15mils.

Heretofore, efforts have focused on reducing the gas permeability of thearticle by addition of gas barrier strengthening fillers, while, at thesame time, trying to reduce the amount of physical haze produced uponorientation of the article. Such efforts, where successful, havegenerally found that to reduce physical haze, the size of the moleculesof the filler had to be significantly small. Generally, it isunderstood, as stated above, that polyamides having a number averagemolecular weight of less than 15000 in a concentration of less than 2percent by weight are needed to sufficiently reduce physical haze.Alternatively, it has been found that, where polyamide domains in thepolyester have been limited to an average number size of from 30 to 200nanometers, physical haze will also be reduced or limited. At least onetheory for this phenomenon is that the polyamide particles are so smallthat they fail to scatter light, particularly in the visible spectra,i.e., the particles do not reflect light to the observer in a mannerdetectable to the naked eye. Moreover, in measuring the physical hazeusing machines such as a colorimeter, it is clear that the physical hazemeasured has been reduced or potentially even eliminated.

Based upon this theory, it should be understood then that, where thoseparticles or domains surrounding the filler are much larger than 200nanometers, say on the order of 400 to 700 nanometers, the haze of thearticle is not only physically measurable, but also may be visible tothe ordinary observer. In fact, at least one journal article expresslyrecognizes that the number and size of the dispersed particles doescreate measured haze. It is further noted therein that stretching makesfor even more measured haze because, firstly, stretching increases thesize of the dispersed particles in a sheet plane and, secondly, thedifference in the anisotropic refractive indices of the matrix and thedispersed phase increases. Thus, some patents have attempted to preventthe stretching or reorienting of the MXD6 domains, for example, byproducing bottles of PET and MXD6 when the polymer is in its moltenstate.

Hence, all of the prior art has focused on the physical haze phenomenonand the reduction or elimination thereof. In contrast, the presentinvention focuses on the visual aspect of the haze property since it isthis characteristic which is believed to be detrimental to the cosmeticappearance and practical use of the article, not the physical haze ofthe article.

Heretofore, however, this “visual haze” or “visible haze” of an articlehas never been considered separate and apart from the physical haze ofthe article, as it is generally immeasurable by traditional physicaltesting of the article. By “visual haze” or “visible haze,” it is meantthat haze which can be observed optically or visually by a person inordinary direct or indirect light. It is the haze that is visible to thenaked eye of the observer, presumably due to the reflectance ortransmittance of the light from the filler domains present in thearticle. It is believed that the visual masking of the physical hazephenomenon results in the elimination or reduction of this “visualhaze,” and can provide an article suitable for commercial use. To thatend, it will be understood that “visual haze” is not a measured physicalproperty to the same extent that the physical haze of an article isdeterminable on a colorimeter or the like, and eliminating or reducingvisual haze may or may not reduce the measured physical haze of thearticle.

Accordingly, eliminating or reducing the “visual haze” of an article,regardless of the physical haze measurements, is seen as highlydesirable to the art, particularly to the plastic container and bottlingindustry. Thus, there remains a need to provide a process by which tomask the visible haze of a transparent article made from polyesterblended with a gas barrier strengthening filler, as well as fortransparent, preferably oriented, articles comprising a polyester/fillerblend that is aesthetically and visually acceptable to the plasticcontainer and bottling industry.

SUMMARY OF THE INVENTION

Broadly, the present invention is directed to the production of atransparent article such as a plastic container or bottle made from amajor component of thermoplastic polymer and a minor component of anincompatible filler. Such an article, particularly when oriented orstretched, will typically produce a haze. It has been unexpectedly foundthat the haze of the transparent article visible to the naked eye may besubstantially masked or, put another way, the visible haze of thearticle may be eliminated or substantially reduced (not necessarily onphysical terms, but on visibility terms), by altering the lightabsorption of the article at wavelengths that at least substantiallycorrelate with the size dimensions of the domains in the thermoplasticpolymer formed upon formation of the article. Importantly, theparticular dimensions with which the wavelengths are to be correlatedare those in the axial plane of the article. It will be understood that,by the term “substantially masked,” it is meant that the alteration ofthe light absorption of the article does not necessarily affect themeasured physical haze of the article, but does substantially reduce ornearly eliminate that haze visible to the naked eye. The measuredphysical haze of the article may not be affected by the light absorbentcomposition at all, may be affected by the composition by only slightlyreducing the measured haze in the article, or may be affectedsignificantly by the light absorbent composition, depending upon theactual light absorbent composition and the amount employed. In anyevent, the visually observable haze of an article is “substantiallymasked” or substantially undetectable to the naked eye of the ordinaryobserver, but physical haze is still generally measurable by acolorimeter to be above ordinarily acceptable limits.

One manner of altering the light absorption of the article is to employan effective amount of one or more light absorbing compositions known toabsorb light at wavelengths which at least substantially cover, and morepreferably, at least substantially correlate to most, if not all, of thedimensions of the domains found in the axial plane of the article. Itwill be appreciated that, for purposes of this invention, at least some,and more preferably, at least a majority of these dimensions of thedomains will necessarily have a size falling within the range from about400 nm to about 700 nm, which substantially corresponds to the visiblespectrum (i.e., from about 380 nm to about 720 nm). By utilizing a lightabsorbing composition, such as a colorant, that has a known region ofabsorption at wavelengths within the visible spectrum, one cansubstantially correlate the wavelengths, in nanometers, within theregion of absorption of the composition to the dimensions, also innanometers, of the filler domains found in the article. By using one ormore particular light absorbing compositions having a region ofabsorption that at least substantially covers the range of dimensions ofthe domains containing the filler found in the thermoplastic filler thatfall within the visible spectrum, it has been found that “visual haze,”as defined herein above, is substantially reduced, if not eliminated,and physical haze is masked in the article.

Furthermore, experimentation has provided a more detailed approximationof the amount of light absorbing composition required to “substantiallycover” the range of dimensions of the domains containing the filler.More particularly, a composition that absorbs light such that X is lessthan 9.6 in the equationX=Σ(1−A _(i))×(N _(i))where A_(i) is the percent of light absorbed at a wavelength i and N_(i)is the number of domains per hundred square microns at wavelength i, andwhere i ranges from 400 nm to 700 nm, is considered to substantiallycover the domains and at least start to reduce the visual haze of anarticle. It will be recognized that an alternative expression of thisequation isX=Σ(L _(i))×(N _(i))where L_(i) is the percent of light not absorbed (i.e. that is availableto reflect) at a wavelength i.

The advantages of the present invention over existing prior art relatingto transparent articles employing polyester and incompatible fillers,which shall become apparent from the description and drawings thatfollow, are accomplished by the invention as hereinafter described andclaimed.

In general, one or more aspects of the present invention may be achievedby a transparent article comprising a thermoplastic polymer matrix; aplurality of domains, each encompassing at least one incompatiblefiller, dispersed in the polyester matrix, the domains having a range ofdimensions in an axial plane of the article, wherein the dimensions ofat least some of the domains in the axial plane of the article fallwithin a range of from about 400 nm to about 700 nm; and an effectiveamount of at least one light absorbent composition, wherein the at leastone light absorbent composition absorbs light in a region of the visiblespectrum at wavelengths that at least substantially covers the range ofdimensions of the domains in the article, to substantially mask anyvisual haze of the transparent article.

One or more other aspects of the present invention may be accomplishedby a process for the production of a transparent article made of a blendof a major component of polyester, a minor component of at least oneincompatible filler dispersed therein, and at least one light absorbentcomposition, comprising blending the filler into the polyester; formingan article into a desired size and shape, wherein domains comprising theincompatible filler are created in the polyester upon formation of thearticle; determining a range of dimensions in the axial plane of thearticle for the domains in the polyester, at least some of thedimensions falling within a range of from about 400 nm to about 700 nm;finding a light absorbent composition that absorbs light in a region ofthe visible spectrum at wavelengths that at least substantially coversthe range of dimensions of the domains in the polyester; and adding aneffective amount of the light absorbent composition to the polyester andthe incompatible filler and forming a different, transparent containerinto the same desired size and shape, to substantially mask any visualhaze in the article.

Still one or more other aspects of the present invention may be achievedby a transparent article comprising a thermoplastic polymer matrix; aplurality of domains, each encompassing at least one incompatiblefiller, dispersed in the polyester matrix, the domains having a range ofdimensions in an axial plane of the article, wherein the dimensions ofat least some of the domains in the axial plane of the article fallwithin a range of from about 400 nm to about 700 nm; and at least onelight absorbent composition, wherein the at least one light absorbentcomposition absorbs light in a region of the visible spectrum such thatX is less than 9.6 in an equationX=Σ(1−A _(i))×(N _(i))where A_(i) is the percent of light absorbed at a wavelength i, whereN_(i) is the number of domains per hundred square microns at wavelengthi, and where i ranges from 400 nm to 700 nm.

Yet one or more other aspects of the present invention may further beachieved by a process for the production of a transparent article madeof a blend of a major component of polyester, a minor component of atleast one incompatible filler dispersed therein, and at least one lightabsorbent composition, comprising blending a selected amount of thefiller into the polyester; forming an article into a desired size andshape, wherein domains comprising the incompatible filler are created inthe polyester upon formation of the article; determining a range ofdimensions in the axial plane of the article for the domains in thepolyester, at least some of the dimensions falling within a range offrom about 400 nm to about 700 nm; blending a selected amount of lightabsorbent composition into the polyester to determine that the lightabsorbent composition absorbs light in a region of the visible spectrumsuch that X is less than 9.6 in the equationX=Σ(1−A _(i))×(N _(i))where A_(i) is the percent of light absorbed at a wavelength i and N_(i)is the number of domains per hundred square microns at wavelength i, andwhere i ranges from 400 nm to 700 nm; and adding that selected amount ofthe light absorbent composition to the polyester and the selected amountof incompatible filler and forming a different, transparent containerinto the same desired size and shape, thereby substantially masking anyvisual haze in the article.

Other aspects of the present invention may be still further achieved bya method for masking visual haze in a transparent article made from amajor component of thermoplastic polymer and a minor component of atleast one incompatible filler, comprising altering light absorption ofthe transparent article at wavelengths that at least substantiallycorrelates with dimensions, in the axial plane of the article, ofdomains in the thermoplastic polymer created upon formation of thearticle and containing the incompatible filler.

DETAILED DESCRIPTION OF THE DRAWINGS

FIG. 1 is a representative sectional, perspective view of a part of anoriented article illustrating domains containing an incompatible fillerdispersed within a thermoplastic polymer matrix;

FIG. 2 is a representative cross-sectional view of a shaped, orientedarticle also illustrating domains containing an incompatible fillerdispersed within a thermoplastic polymer matrix;

FIG. 3 is an enlarged sectional view of one domain within thethermoplastic polymer matrix of FIG. 2;

FIG. 4 is an enlarged sectional view of the domain of FIG. 3 taken alongline 4-4 in FIG. 3;

FIG. 5 is a photomicrograph of a portion of a transparent article priorto orientation;

FIG. 6 is a photomicrograph of the same portion of the transparentarticle of FIG. 5 after orientation to a desired shape and size;

FIG. 7 is a representative graph of the data obtained from analysis ofthe dimensions of the MXD-6 domains of a 500 ml bottle prepared frompolyester and MXD-6;

FIGS. 8A, 8B, and 8C are representative absorption spectra of variousyellow, red, and blue colorants, respectively;

FIGS. 9A, 9B, 9C, and 9D are representative absorption spectra ofvarious green, orange, purple and pink colorants, respectively;

FIG. 10 is a representative comparison graph comparing the plot of thenumber of domains per hundred square microns present in an article basedupon its size in nanometers with the % of light absorbed of a particulargreen colorant designated Sprite Green, over that a range of wavelengthsin nanometers for the same article;

FIG. 11 is a representative comparison graph comparing the plot of thenumber of domains per hundred square microns present in an article basedupon its size in nanometers with the % light absorbed of various greenand red colorants over a range of wavelengths in nanometers for the samearticle; and

FIG. 12 is a representative comparison graph comparing the plot of thenumber of domains per hundred square microns present in an article basedupon its size in nanometers with the % light absorbed of various blueand red colorants over a range of wavelengths in nanometers for the samearticle.

DETAILED DESCRIPTION OF THE INVENTION

In accordance with the present invention, shaped transparent articlescomprising thermoplastic polymer and at least one incompatible fillerdispersed therein are provided wherein haze in the article, normallyvisible to the naked eye of the ordinary observer, and produced mostcommonly by stretching or orienting the thermoplastic polymer and fillerblend during production of the article, has been substantially masked.Such articles are especially useful in the packaging industry when inthe form of a container or bottle.

The present invention solves the haze problem in a manner heretoforenever contemplated. It masks haze that is visible to the naked eye ofthe observer of the article and does not require the use of lowmolecular weight fillers or fillers having domain dimensions in thearticle of less than about 200 nm or otherwise below the lowestwavelengths of the visible spectrum (i.e., less than about 380-400 nm),so as to produce an article having reduced physical haze below about 4%per 15 mil thickness of the article. Instead, the present inventionmasks any visible haze by altering the light absorption of the articleat wavelengths that at least substantially covers the range of thedimensions of the filler domains in the axial plane of the article.

By the phrase “at least substantially covers” and the phrase “at leastsubstantially correlates” also used herein, both of which can be usedinterchangeably, it is meant that the range of wavelengths, innanometers, at which the light absorbent composition employed absorbslight in the visible spectrum is approximate to or is greater than therange of dimensions of the filler domains in the axial plane of thearticle, to the extent that those dimensions are somewhere between about400 nm and about 700 nm, i.e., are in the visible spectrum. Thus, itwill be appreciated that the range of dimensions of the filler domainsdoes not have to completely cover the entire visible spectrum. It willalso be appreciated that the range of wavelengths need not necessarilycover the entire range of dimensions of the filler domains provided inthe article to mask the haze, but rather that they cover enough of therange of dimensions to substantially mask the haze. For instance, it ispossible that the range of dimensions of the filler domains provided inthe article is greater than or at least partially falls outside of thevisible range. The range of wavelengths of the light absorbentcomposition need only substantially cover that range of dimensions thatfalls within the visible spectrum for the present invention. In anotherinstance, if a light absorbent composition is capable of absorbing lightin all but a very small region where only a few domains exist, it hasbeen determined that the observer would not be able to see the haze ofthe container or bottle regardless of the fact that the light at aparticular wavelength is not absorbed where a few domains may exist.That is, the remaining existence of a few particular domains havingdimensions that do not correspond (i.e., fall outside the range of) tolight absorbing wavelengths of the light absorbent composition employedis seen as de minimus to the present invention, and will not preventsubstantial masking of the visual haze in the article. For practicalpurposes, masking of the visual haze will be deemed sufficient if thecosmetic appearance of the article having substantially masked haze isacceptable to the interested industry, in particular the container andbottling industry, as a transparent article that can be practically usedin commerce.

In further defining the phrases “at least substantially covers” and “atleast substantially correlates” above, it will also be appreciated thatthe greater the number of domains having a particular dimension in theaxial plane of the article, desirably the greater the light absorptionat the matching wavelength should be. However, it has been found thatthere need not necessarily be a one to one or greater correspondencebetween the intensity (i.e., amount) of the absorption for the lightabsorbent composition and the number of domains having a particulardimension. If substantial light is absorbed by the light absorbentcomposition at a wavelength that correlates to a particular dimensionfor a domain in the article, then it is believed that at leastsignificant masking of the haze will occur.

More particularly, it has been found that a light absorbent compositionthat absorbs light in the visible spectrum such that X is less than 9.6in the equationX=Σ(1−A _(i))×(N _(i))where A_(i) is the percent of light absorbed at a wavelength i and N_(i)is the number of domains per hundred square microns (10⁸ nm²) atwavelength i, and where i ranges from 400 nm to 700 nm (i.e., thevisible spectrum), is considered to substantially cover the domains andwill at least start reducing the visual haze of an article.

Stated another way, to reduce visual haze of an article, a lightabsorbent composition must be included in the relevant part of anarticle, typically the single continuous portion of the article wherehaze is noticed such as the sidewall of a container or bottle. Thatlight absorbent composition must be capable of absorbing light in thevisible spectrum of that single, continuous portion of the article suchthat, when absorbance is determined on that single continuous portion ofthe article without an incompatible filler present, X is less than 9.6in the equationX=Σ(L _(i))×(N _(i))where L_(i) is the percent of light not absorbed (i.e. that is availableto reflect) at a wavelength i, and N_(i) is the number of domains perhundred square microns (10⁸ nm²) at wavelength i, and where i rangesfrom 400 nm to 700 nm (i.e., the visible spectrum) If X is less than9.6, then the ordinary observer will at least begin to see a reductionin the visual haze of the article.

Moreover, as X gets smaller, the visual haze of the article will befurther reduced. Thus, while X must be less than 9.6 in the aboveequation for a reduction in visual haze to start to be noticed, X lessthan 9.5 is preferred, and X less than 9 is more preferred, and X lessthan 7.5 is even more preferred. It will be appreciated that where nodomains are present (i.e., N=0), X will necessarily be 0, and no hazewill be encountered. Likewise, where the colorant or light absorbentcomposition has absorbed most of the light available for reflection overa range of wavelengths, then the percent of light transmitted orreflected is low (i.e., L approaches 0) and therefore, X will be lowunless there is an unusually high number of domains of the same size asthose wavelengths. In other words, the total amount of relative lightavailable for reflectance (i.e., that is not absorbed) across the entirevisible spectrum, from about 400 nm to about 700 nm, must be less than9.6. The “total amount of relative light” is calculated as the sum ofall the light at each wavelength between about 400 nm and about 700 nmwith a greater amount of light required for each wavelength havingdomains at that wavelength. Thus, the relative amount of light requiredto be absorbed is weighted toward the number of domains present in thewavelength.

It will be appreciated that the determination of whether a lightabsorbent composition will absorb light for a particular article belowan X threshold is relatively simple and can be determined without undueexperimentation. A_(i) is the percent of light absorbed by the articlehaving the colorant without the incompatible filler at wavelength i;L_(i) is the percent of light available to reflect at wavelength i,where i is 400 nm to 700 nm. These percentages can be calculated uponmeasuring the absorbance of the composition, it being understood thatA_(i)+L_(i)=1. In most instances, L_(i) will be 1 minus the percentabsorbed, or the percent of light available for reflectance. Thesemeasurements can be obtained using the process described below. N_(i) isthe number of domains per hundred square microns at wavelength i, wherei is 400 nm to 700 nm. N can be measured by SEM and normalized to squaremicrons.

The intensity of the light at wavelength i may be pertinent in someinstances, and can be factored into the equation as I_(i) as followsX=300Σ(L _(i))×(N _(i))×(I _(i))where I_(i) is the intensity of a source of light at the wavelengthdivided by the total light between 400 nm to 700 nm. Where aspectrophotometer that measures the percent light is used, I_(i) is1/300 and, therefore, multiplying by 300 normalizes the light to acommon standard.

In essence, it has been found that employing a higher concentration oflight absorbent composition to the article may help to more fully maskthe visible haze in the article where the light absorbent compositionabsorbs light at a particular wavelength less intensely than at otherwavelengths and/or where a great number of domains exist at a particulardimension corresponding to that particular wavelength. It is believedthat any required intensity of the light absorbed can be calculated orpredetermined without undue experimentation based upon the concentrationof the light absorbent composition, the thickness of the article andother known parameters and coefficients according to the law ofBeer-Lambert-Bouguer.

Referring now to the drawings, a section of a shaped, transparentarticle, generally indicated by the numeral 10 in FIG. 1, isillustrated. As shown, the section 10 has been oriented or stretched inall directions within the axial plane of the article, including both theradial (X) and axial (Y) directions, as indicated by the arrows. By theterm “axial plane,” it is meant that the general plane of the article isessentially parallel to the surface of the article, or put another way,that the general plane of the article is substantially perpendicular tothe line of sight of the observer.

The section 10 comprises a thermoplastic polymer matrix 12 havingdiscrete particles 14 of an incompatible filler dispersed therein and,where the incompatible filler is not extensible or deformable likepolyester and other thermoplastic polymers (e.g., clay particles), voids16 encompass the particles 14. Assuming the use of spherical fillerparticles 14 upon blending in the polymer matrix 12, and where theparticles have been dispersed uniformly and an article has been orientedevenly in all directions within the axial plane, a cross-section of thevoids 16 would be, in theory, circular, as shown here and in FIG. 4,when viewed perpendicular to the axial plane. In practice however,dispersion of the filler and stretching of the article is not precise,and irregular-shaped voids are most often created, having variouslength, width and height dimensions.

It will be understood that the incompatible filler may be extensible anddeformable like the thermoplastic polymer as well. Such fillers maythemselves include various thermoplastic polymers, like polyamides. Inthe case of a polyester matrix, the incompatible filler would stretchlike the polyester and form a stretched, discrete minor phase 17 withinthe polyester matrix. This phase 17 will essentially include not onlythe particles 14 but also the voids 16 in FIG. 1. Thus, the extensiblefiller will be stretched to fill-in all of the voids. In FIG. 1, theminor phase 17 of the filler will compass the entire circle identifiedby the numeral 16 as well as the circle therein identified by thenumeral 14.

It is also known that, oftentimes, given the irregular shapes that mayform, two or more of these discrete minor phases of the filler may cometogether to form one larger structure. For purposes of this invention,numerals 17 and 27 in FIGS. 1-4 will be referred to hereinafter as “thediscrete phases” or “the minor phases” of the filler, unless otherwisestated, and shall include the area or volume denoted by both thenumerals 16 and 14 in FIG. 1, and the numerals 26 and 24 in FIGS. 2-4,respectively. This language associates the present invention with theuse of extensible thermoplastic polymers as the incompatible filler, butshould not necessarily be limited in scope thereto, the presentinvention being set forth by the scope and spirit of the attachedclaims.

Unlike the representative drawing, sectioning the article along any onespecific axial plane will penetrate the discrete minor phases 17 atvarious places through the height of each phase unless, as shown here,all minor phases 17 are evenly parallel on the specific axial plane.Thus, some discrete phases should appear smaller than others on any onespecific axial plane. Likewise, cutting the article along any onespecific transverse plane will penetrate the discrete phases at variousplaces through the length and/or width of each discrete phase unless thephases are unidirectionally stacked on each other within that plane.Thus, some discrete phases should appear longer than others on any onespecific axial plane.

In FIG. 2, a section of a wall of a shaped article, generally indicatedby the numeral 20, is illustrated. Such an article may be a plasticcontainer or bottle. As described previously for FIG. 1 above, thissection 20 of the article includes a thermoplastic polymer matrix 22having discrete particles 24 of an incompatible filler dispersed thereinand surrounded by voids 26. Based upon the FIGS. 3 and 4, it will beappreciated that this article 20 is also oriented or stretched in alldirections within the axial plane of the article, in a manner similar tothat shown in FIG. 1.

FIGS. 3 and 4 are sectional views illustrating enlargement of a sectionof the shaped article of FIG. 2, wherein the filler particle 24 iscontained in the void 26 and is entrapped within the continuousthermoplastic polymer matrix 22. Again, where the filler is anextensible, deformable thermoplastic polymer, the entire area or volumedenoted by the numerals 24 and 26 is the minor phase 27 of the filler.These phases 27 result from the shaped article being stretched asdiscussed herein above.

Upon formation of the article, a domain 28 is created in the polymermatrix 22 which essentially includes both the discrete particle 24 andvoid 26, or the entire minor phase 27 of the incompatible filler. Wherethe incompatible filler used in the present invention is moldable andstretchable like the polymer employed in the article, orientation orstretching of the article will cause the incompatible filler, like thepolymer, to spread along the axial plane of the article and to narrow inthe transverse plane of the article as the wall of the article becomesthinner. However, in instances where the filler is not stretchable likethe polymer, a void or voids 26 may be left between the filler and thepolymer. Where a polyamide and another thermoplastic polymer other thanthe thermoplastic polymer employed as the matrix polymer, e.g.,polyester, are utilized as the filler, the void left, if any, willgenerally be de minimus since both of the thermoplastic polymers arestretchable and deformable. Thus, the domains created in the matrixpolymer are essentially the volume of the minor phases themselves.Nevertheless, for purposes of this invention, it will be understoodthat, where non-deformable filler particles are utilized, a domain 28includes not only the volume of the filler particle 24, but also anyadditional volume in the article of any void 26 between the fillerparticle 24 and the polymer 22. Where the article has not beenstretched, the domain will match the volume of the filler particle.

The present invention is particularly concerned with those domainshaving a dimension in the axial plane of the article within the range offrom about 400 nm to 700 nm. Referring to FIGS. 3 and 4, the dimensionof a domain is the diameter of the domain. Thus, in FIG. 3, thedimension can be seen as extending from one end 29 to the other end 29′of the domain. In FIG. 4, the dimension of the domain shown is anydiameter of the circle. However, it will be appreciated that more oftenthe domain in the axial plane of the article will be ellipsoidal innature and will have a longer diameter in one direction, say the Ydirection, than in another, say the X direction. In this instance, thedimensions of relevance may be the longest diameter of the domain (i.e.,the major axis of the domain which, in this scenario, is in the axial Ydirection), or the diameter of the dimension perpendicular to thelongest diameter in the axial plane (i.e., the minor axis of the domainwhich is in the radial (X) direction). It has been found that domainshaving dimensions of between about 400 nm and about 700 nm show up inthe article as visual haze. Not coincidentally, this range is also therange of the visible spectrum. Thus, any domain having a dimensionfalling within the range of the visible spectrum might be visible ashaze.

It will also be understood that not all domains must necessarily havedimensions that fall within the range of the visible spectrum, but it isonly those domains with which the present invention is concerned. Intheory, if a sufficient number of domains having dimensions in thevisible spectrum are found, then the container will have haze regardlessof the number of domains that do not have dimensions falling within thevisible spectrum.

Referring to FIGS. 5 and 6, photomicrographs of a transparent articlebefore (preform) and after orientation (container), respectively, showthat the domains created in a polyester during formation, and here,orientation, of the article, and containing the incompatible filler,indeed increase in size upon orientation. In the transparent, non-hazypreform, the domains are on the order of about 200 nm or less, wellbelow the visible spectrum. However, in FIG. 6, the stretching processduring orientation of the container has increased the size of thedomains. As shown, the length dimensions of the domains are well withinthe visible spectrum.

Also, the domains does not have to cover the entire visible spectrum.The domains' dimensions may comprise a range that extends into theregion of the visible spectrum, i.e., the range of dimensions exceeds400 nm or starts below 700 nm, or may fall only within a particularrange within the region of the visible spectrum, e.g., range from about450 nm to about 580 nm.

Once the range of dimensions of the filler domains is determined orotherwise found, a light absorbent composition can be found whichabsorbs light at wavelengths in the region of the visible spectrum thatat least substantially covers the range of dimensions of the domains or,stated another way, that provides for X being less than 9.6 in theequationX=Σ(1−A _(i))×(N _(i))where A_(i) is the percent of light absorbed at a wavelength i and N_(i)is the number of domains per hundred square microns (10⁸ nm²) atwavelength i, and where i ranges from 400 to 700. However, determiningthe range of dimensions of the filler domains does not have to be doneexperimentally or by measurement. All that is required is that it bedetermined that a substantial number of domains have dimensions fallingwithin the visible spectrum, i.e., from about 400 nm to about 700 nm.This can be as simple as determining that the container or other articlehas physical haze that is visible to the naked eye. It is believed thatif the article has “visual haze,” it necessarily has domains havingdimensions falling in the region of the visible spectrum.

The light absorption of the light absorbent composition is often knownto those skilled in the art, and may be found or determined by anymanner known in the art. One method for determining the light absorptionof a light absorbent composition is to analyze the absorption spectra ofthe composition. Once the region of absorption for that spectrum of thecomposition is known, that spectrum can be considered in view of therange of dimensions of the filler domains present, and/or can be used tocalculate the percent of light available for reflecting at any of aselected wavelength. If the light absorption spectrum at leastsubstantially covers the range of dimensions, or if X is less than 9.6,more preferably less than 9.5, even more preferably less than 9 and mostpreferably less than 7.5, then the composition can be used in thearticle. When the article is oriented or stretched, it has beenunexpectedly found that the composition in the article absorbs light ina manner that substantially masks the haze of the article.

Turning to the components of the article, the present invention includesa thermoplastic polymer matrix having an incompatible filler dispersedtherein. The incompatible filler is preferably present in an amount ofabout 0.5 to about 50 percent by weight based on the weight of polymer.In one embodiment, a polyester, preferably PET, may comprise from about99.5 to about 50 percent by weight of the article as the major componentand the incompatible filler, preferably MXD-6, may comprise from about0.5 to about 50 percent by weight of the article as the minor component.

It will be understood that the thermoplastic polymer suitable for use inthe present invention can be made into a film or sheet. The presentinvention is not, however, limited to films and sheets. The article ofthe present invention also includes containers, bottles, trays, bases,lids, etc. Such article may be manufactured or formed into a desiredsize and shape using any processing techniques known in the art,including blow molding, injection molding, extrusion, and the like.Articles of the present invention may also include a wall of a largerarticle. Moreover, the article of the present invention is desirablytransparent. By “transparent,” it is meant that one can see through thearticle, i.e. is not opaque. It will be understood that the transparentarticle may be colored, but that one can clearly see through at leastone wall or sheet of the article.

The major component of the article of the present invention is thethermoplastic polymer matrix. Suitable thermoplastic polymers for use inthe present invention include any thermoplastic homopolymer, copolymer,terpolymer, or blend. Examples of thermoplastic polymers includepolyamides, such as nylon 6, nylon 66 and nylon 612, linear polyesters,such as polyethylene terephthalate, polybutylene terephthalate,polytrimethylene terephthalate, polyethylene isophthalate, andpolyethylene naphthalate, branched polyesters, polystyrenes,polycarbonate, polyvinyl chloride, polyvinylidene dichloride,polyacrylamide, polyacrylonitrile, polyvinyl acetate, polyacrylic acid,polyvinyl methyl ether, ethylene vinyl acetate copolymer,poly(3-phenyl-1-propene), poly(vinylcyclohexane), ethylene methylacrylate copolymer, and low molecular weight polyolefins having 2 to 20carbon atoms, such as polyethylene, polypropylene, ethylene-propylenecopolymers, poly(1-hexene), poly(4-methyl-1-pentene), poly(1-butene),and poly(3-methyl-1-butene). Preferably, the thermoplastic polymer usedin the present invention comprises a polyester polymer or copolymer.

The polyester phase may be any article-forming polyester or copolyestersuch as a polyester capable of being cast, extruded or molded into anarticle. The polyesters should have a glass transition temperaturebetween about 50° C. and about 150° C., preferably about 60°-100° C.,should preferably be orientable, and have an I.V. of at least 0.55,preferably 0.6 to 1.0 deciliters/gram, as determined by ASTM D-4603-86at 30° C. in a 60/40 by weight mixture of phenol and tetrachloroethane.Suitable polyesters include those produced from aromatic, aliphatic orcycloaliphatic dicarboxylic acids of from 4 to about 40 carbon atoms andaliphatic or alicyclic glycols having from 2 to about 24 carbon atoms.

Polyesters employed in the present invention can be prepared byconventional polymerization procedures well known in the art. Thepolyester polymers and copolymers may be prepared, for example, by meltphase polymerization involving the reaction of a diol with adicarboxylic acid, or its corresponding diester. Various copolymersresulting from use of multiple diols and diacids may also be used.Polymers containing repeating units of only one chemical composition arehomopolymers. Polymers with two or more chemically different repeatunits in the same macromolecule are termed copolymers. The diversity ofthe repeat units depends on the number of different types of monomerspresent in the initial polymerization reaction. In the case ofpolyesters, copolymers include reacting one or more diols with a diacidor multiple diacids, and are sometimes referred to as terpolymers.

As noted herein above, suitable dicarboxylic acids include thosecomprising from about 4 to about 40 carbon atoms. Specific dicarboxylicacids include, but are not limited to, terephthalic acid, isophthalicacid, naphthalene 2,6-dicarboxylic acid, cyclohexanedicarboxylic acid,cyclohexanediacetic acid, diphenyl-4,4′-dicarboxylic acid,1,3-phenylenedioxydiacetic acid, 1,2-phenylenedioxydiacetic acid,1,4-phenylenedioxydiacetic acid, succinic acid, glutaric acid, adipicacid, azelaic acid, sebacic acid, and the like. Specific esters include,but are not limited to, phthalic esters and naphthalic diesters.

These acids or esters may be reacted with an aliphatic diol preferablyhaving from about 2 to about 24 carbon atoms, a cycloaliphatic diolhaving from about 7 to about 24 carbon atoms, an aromatic diol havingfrom about 6 to about 24 carbon atoms, or a glycol ether having from 4to 24 carbon atoms. Suitable diols include, but are not limited to,1,4-butenediol, trimethylene glycol, 1,6-hexanediol,1,4-cyclohexanedimethanol, diethylene glycol, resorcinol, andhydroquinone.

Polyfunctional comonomers can also be used, typically in amounts of fromabout 0.1 to about 3 mole percent. Suitable comonomers include, but arenot limited to, trimellitic anhydride, trimethylopropane, pyromelliticdianhydride (PMDA), and pentaerythritol. Polyester-forming polyacids orpolyols can also be used. Blends of polyesters and copolyesters may alsobe useful in the present invention.

One preferred polyester is polyethylene terephthalate (PET) formed fromthe approximate 1:1 stoichiometric reaction of terephthalic acid, or itsester, with ethylene glycol. Another preferred polyester is polyethylenenaphthalate (PEN) formed from the approximate 1:1 to 1:1.6stoichiometric reaction of naphthalene dicarboxylic acid, or its ester,with ethylene glycol. Yet another preferred polyester is polybutyleneterephthalate (PBT). Copolymers of PET, copolymers of PEN, andcopolymers of PBT are also preferred. Specific copolymers andterpolymers of interest are PET with combinations of isophthalic acid orits diester, 2,6 naphthalic acid or its diester, and/or cyclohexanedimethanol.

The esterification or polycondensation reaction of the carboxylic acidor ester with glycol typically takes place in the presence of acatalyst. Suitable catalysts include, but are not limited to, antimonyoxide, antimony triacetate, antimony ethylene glycolate,organomagnesium, tin oxide, titanium alkoxides, dibutyl tin dilaurate,and germanium oxide. These catalysts may be used in combination withzinc, manganese, or magnesium acetates or benzoates. Catalystscomprising antimony are preferred. Another preferred polyester ispolytrimethylene terephthalate (PTT). It can be prepared by, forexample, reacting 1,3-propanediol with at least one aromatic diacid oralkyl ester thereof. Preferred diacids and alkyl esters includeterephthalic acid (TPA) or dimethyl terephthalate (DMT). Accordingly,the PTT preferably comprises at least about 80 mole percent of eitherTPA or DMT. Other diols which may be copolymerized in such a polyesterinclude, for example, ethylene glycol, diethylene glycol,1,4-cyclohexane dimethanol, and 1,4-butanediol. Aromatic and aliphaticacids which may be used simultaneously to make a copolymer include, forexample, isophthalic acid and sebacic acid.

Preferred catalysts for preparing PTT include titanium and zirconiumcompounds. Suitable catalytic titanium compounds include, but are notlimited to, titanium alkylates and their derivatives, titanium complexsalts, titanium complexes with hydroxycarboxylic acids, titaniumdioxide-silicon dioxide-co-precipitates, and hydratedalkaline-containing titanium dioxide. Specific examples includetetra-(2-ethylhexyl)-titanate, tetrastearyl titanate,diisopropoxy-bis(acetyl-acetonato)-titanium,di-n-butoxy-bis(triethanolaminato)-titanium, tributylmonoacetyltitanate,triisopropyl monoacetyltitanate, tetrabenzoic acid titanate, alkalititanium oxalates and malonates, potassium hexafluorotitanate, andtitanium complexes with tartaric acid, citric acid or lactic acid.Preferred catalytic titanium compounds are titanium tetrabutylate andtitanium tetraisopropylate. The corresponding zirconium compounds mayalso be used.

The polymer of this invention may also contain small amounts ofphosphorous compounds, such as phosphates, and a catalyst such as acobalt compound, that tends to impart a blue hue. Also, small amounts ofother polymers such as polyolefins can be tolerated in the continuousmatrix.

The melt phase polymerization described above may be followed by acrystallization step, then a solid phase polymerization (SSP) step toachieve the intrinsic viscosity necessary for the manufacture of certainarticles such as bottles. The crystallization and polymerization can beperformed in a tumbler dryer reaction in a batch-type system.Alternatively, the crystallization and polymerization can beaccomplished in a continuous solid state process whereby the polymerflows from one vessel to another after its predetermined treatment ineach vessel. The crystallization conditions preferably include atemperature of from about 100° C. to about 150° C. The solid phasepolymerization conditions preferably include a temperature of from about200° C. to about 232° C., and more preferably from about 215° C. toabout 232° C. The solid phase polymerization may be carried out for atime sufficient to raise the intrinsic viscosity to the desired level,which will depend upon the application. For a typical bottleapplication, the preferred intrinsic viscosity is from about 0.65 toabout 1.0 deciliter/gram, as determined by ASTM D-4603-86 at 30° C. in a60/40 by weight mixture of phenol and tetrachloroethane. The timerequired to reach this viscosity may range from about 8 to about 21hours. In one embodiment of the invention, the article-forming polyesterof the present invention may comprise recycled polyester or materialsderived from recycled polyester, such as polyester monomers, catalysts,and oligomers.

Suitable fillers for the present invention include, but are notnecessarily limited to, those polymers, clays, minerals, and othercompounds known to be chemically unreactive with the thermoplasticpolymer matrix so as to provide discrete domains within the polymermatrix. Typically, such fillers will be provided in order to improve aphysical or mechanical property of the polyester for a desired purpose.For example, in many food and beverage packaging applications, reducinggas permeability of the container or bottle in which the food orbeverage is stored is often desired. Thus, gas barrier strengtheningfillers are added to improve the container's ability to prevent oxygenor other gases from passing through the container wall and into thecontainer or bottle, thereby possibly spoiling the food or beverageinside.

The incompatible fillers of the present invention are on the order offrom about 10 nanometers to less than about 1 micron in diameter. Whilethere are many larger particles which may increase the gas barrierstrengthening properties of the container or bottle, the presentinvention refers to those particle fillers which create domains havingdimensions of from about 10 nanometers up to about 1 micron, and which,more particularly, create domains having dimensions of from about 400nanometers to about 700 nanometers. Thus, fillers having particle sizeshigher or lower than the about 400 to about 700 nanometer range may beemployed so long as at least some of the domains created uponorientation fall within that range, even if other domains are createdthat fall outside of that range.

The most preferred incompatible fillers are polyamides. Suitablepolyamides include aliphatic, cycloaliphatic and aromatic polyamides. Asnoted above, the amount of polyamide to be blended with the polyester ispreferably from about 0.5 to about 50 weight percent, more preferablyfrom about 3 to about 15 weight percent. Also preferred incompatiblefillers are nanoclays, glass beads, and fibers.

Where a polyamide is employed as the incompatible filler, the polyamidecomponent of the present invention may be represented by repeating unitA-D, where A is the residue of a dicarboxylic acid including adipicacid, isophthalic acid, terephthalic acid, 1,4-cyclohexanedicarboxyolicacid, resorcinol dicarboxylic acid, naphthalene-2,6-dicarboxylic acid ora mixture thereof, and D is the residue of a diamine includingm-xylylene diamine, p-xylylene diamine, hexamethylene diamine, ethylenediamine, 1,4-cyclohexanedimethylamine or a mixture thereof. Preferredpolyamides that can be used in this invention includes poly(m-xylyleneadipamide) or a copolymer thereof, isophthalic or terephthalicacid-modified poly(m-xylylene adipamide), nylon 6, nylon 6,6 or amixture thereof, poly(hexamethylene isophthalamide), poly(hexamethyleneadipamide-co-isophthalamide), poly(hexamethyleneadipamide-co-isophthalamide, poly(hexamethyleneadipamide-co-terephthalamide) or poly(hexamethyleneisophthalamide-co-terephthalamide).

Suitable polyamides may also contain small amounts of trifunctional ortetrafunctional comonomers including trimellitic anhydride, pyromelliticdianhydride or other polyamide forming polyacids and polyamines known inthe art.

The I. V. for the polyamides to be blended with the polyester ispreferably less than about 1.0 deciliters/gram, and most preferably lessthan about 0.7 deciliters/gram as determined by ASTM D-4603-86 at 25° C.in a 60/40 by weight mixture of phenol and tetrachloroethane at aconcentration of 0.5 g/100 ml (solvent).

The preparation of polyamides and polyester/polyamide blend compositionsis well known in the art and any methods for obtaining thesecompositions may be employed.

In one embodiment of the present invention, the preferred polyamide ispoly(m-xylylene adipamide), also often referred to as MXD-6. MXD-6 ispreferably used in an amount ranging from about 1 to about 30 percent byweight relative to the polyester resin. Also preferred are other MXDs,wherein all or part of the units derived from adipic acid are replacedby units derived from dicarboxylic acid with 6 to 24 carbon atoms otherthan adipic acid, such as for example, sebacic, azelaic, and dodecanoicacid, may be employed.

The invention does not require but may include the use or addition ofany of a plurality of organic or inorganic materials, such as but notlimited to, anti-blocks, anti-stats, plasticizers, stabilizersnucleating agents, etc. These materials may be incorporated into thepolymer matrix, into the dispersed minor phase, or may exist as separatedispersed phases.

Mixing or blending of a polyester resin and polyxylylene amide may becarried out in an extruder under known conditions of temperature andshear forces so as to ensure proper mixing and to create a fine, stabledispersion of the polyamide in the polyester matrix. In one embodiment,the polyester and filler of the present invention is generally preparedusing a well known technique known as the “shake and bake” method.Typically, polyester, such as PET, and polyamide polymers, as well asthe light absorbent composition when it is time, are mixed into amasterbatch, shaken until thoroughly mixed and poured into the hopper tobe extruded or molded into preforms as is well known in the art. Shearrates higher than 100 s⁻¹ may be used when melt-mixing polyamide. Themelt viscosity ratio of the polyester to the polyxylylene amide,elevated at 280° C. at a shear rate of 100 s⁻¹, is preferably betweenabout 3:1 and 8:1.

Once blended, the blended components may then be made into a desiredsize and shape of an article. In one embodiment, the component can beblow molded into the shape of a bottle or other container of aparticular size. Once molded, a determination that at least some of thefiller domains in the article have dimensions in the axial plane of thecontainer of from about 400 nm to about 700 nm can be made. Such adetermination may be made simply by determining that the article hashaze visible to the naked eye. In one embodiment, where a more precisedetermination is desired, the minor phase of the thermoplastic polymerfiller can be dissolved out of the polyester matrix by using formicacid. Use of cold formic acid, i.e., formic acid at room temperature, ispreferred. As the temperature of hot formic acid is above the Tg ofpolyester, it is possible that the domains could be relaxed or expandeddepending upon the location of the domains. Once dissolved, ameasurement of the domain dimensions can be taken as may be known in theart. For example, one method of measuring the domain dimensions is toobtain a scanning electron microscope (SEM) photomicrograph of thearticle and measure the domain using appropriate equipment andtechniques such as by using LuciaM (available from Laboratory Imaging,Prague, Czech Republic) software on the photomicrographs realized at5000×. It will be appreciated that, however, that the dimensionsmeasured may not all be the longest dimensions for any one domain,although theoretically they should be. In one embodiment, measurementswere taken of both the preforms and the container in both the radial andaxial directions in the axial plane of the container.

Once it is determined that the range of dimensions in the axial plane ofthe container for the domains created in the polymer matrix afterforming the container includes at least some of the dimensions fallingwithin a range of from about 400 nm to about 700 nm, a light absorbentcomposition can be found that absorbs light in a region of the visiblespectrum at wavelengths that at least substantially covers the range ofdimensions of the domains in the container. As noted above, this can bedone by any means known in the art, including experimentally by addingvarious compositions to a similarly blown container, experimentally byproviding sleeves of colored films over the article, by review of thespectrum of the various light absorbent compositions proposed to beused, or by determining whether X in the equationX=Σ(1−A _(i))×(N _(i))where A_(i) is the percent of light absorbed at a wavelength i and N_(i)is the number of domains per hundred square microns (10⁸ nm²) atwavelength i, and where i ranges from 400 nm to 700 nm (i.e., thevisible spectrum), is less than 9.6, preferably less than 9.5, morepreferably less than 9, and most preferably less than 7.5.

Preferably, these compositions will be colorants commonly used inpigmenting or dying of plastics. Essentially any colorant (either a dyeor a pigment) may be employed provided it has a suitable spectrum asrequired for the present invention. The colorant may or may not becompatible with (i.e., hydrophilic to) the polyamide or other filleremployed.

The colorant can be mixed into the polyester/filler matrix or,alternatively, can be made of a separate film overlaying the articleshowing visible haze. Known multi-layering techniques can be used toadhere the layers together. Generally, however, the light absorbentcomposition may be in a separate film overlaying a separate layer of thearticle comprising the polyester/filler matrix.

Thus, in a multilayer container, at least one layer of the multi-layercontainer may comprise the thermoplastic matrix with the dispersedincompatible filler and another, different layer may comprise the lightabsorbent composition.

It is also possible that the light absorbent composition can come fromthe polyester itself. If the range of dimensions for the domains is suchthat yellowing of the polyester can provide light absorption in a rangethat substantially covers that range of dimensions of the domains, noadditional composition will be necessarily required. Hence, theyellowing component of the polyester itself may serve as the lightabsorbent composition.

Alternatively, and as noted above, an effective amount of the lightabsorbent composition may be added to the thermoplastic polymer and theincompatible filler blend in any manner known in the art. Anothercontainer may then be made using known container-making techniques suchas blow molding. This new transparent container having a polyestermatrix with an incompatible filler and a light absorbent compositiondispersed therein should then be made into the same desired size andshape. A different size and shape may provide different dimensions tothe domains found in the article and could change the range of thedimensions and thus, the light absorbent composition required. It shouldthen be evident that the light absorbent composition can substantiallymask the haze in the container.

In order to demonstrate practice of the present invention, a number ofpreforms were extruded from a blend of polyester, namely polyethyleneterephthalate (PET) and about 5 percent by weight polyamide, namely,poly(-xylylene adipamide), commonly known as MXD-6 and available fromMitsubishi Gas Chemical (Harada, M., Plastics Engineering, 1998). Thepreforms also contained 0.04 percent by weight1,2,4,5-benzenetetracarboxylic dianhydride, or pyromellitic dianhydride(PMDA). Upon extrusion, a number of bottle preforms were produced havingMXD-6 dispersed within a PET matrix. Some of the preforms were then blowmolded into bottles, each bottle having essentially an identical shapeand a size of 500 ml's. Upon construction of the bottles, each was cutin both the vertical transverse plane and the horizontal transverseplane and etched in cold formic acid for about 60 minutes, the samplesthen were washed with water till neutral pH and then with acetone.Obtained samples were metalized (gold) with Agar Auto sputter Coaterunder subsequent condition: 20 mA for 20 seconds with argon flow. Thelongest dimensions of the remaining MXD-6 domains were measured usingLuciaM software on the SEM photomicrographs realized at magnification of5000×. The photomicrographs were obtained from cutting the bottle in thevertical and horizontal transverse planes and observing the longestdimension which necessarily was the dimension parallel to the surface ofthe article. In FIG. 7, the distribution of the results obtained fromthe measure of the longest dimension in the vertical transverse plane,i.e., the radial (X) direction based upon the Figures above, isreported.

Obtained data shows that during the blow-molding from preform to bottle,the MXD-6 domains increase in diameter. Generally, an increase of theaverage dimension from about 160 nm (preform average) to about 500 nm(bottle average) has been found. That is an increase factor of 3:1 inthe radial direction. FIGS. 5 (preform) and 6 (oriented bottle) showthis phenomena.

Based upon the data, the domains were found to range in length fromabout 400 nm to about 600 nm, with the greatest number of domains havinga dimension of about 500 nm. This is within the visible spectrum.Viewing the visible spectrum, it can be determined that the region atabout 500 nm is the green region (green 512 nm). From review of thechromatic circle, it can be seen that the complementary color whichabsorbs light in this same region is red. Therefore, attempts were madeto find a red colorant which would absorb light in the green regioncorresponding to the range of dimensions of the domains. It will beappreciated that any colorant that absorbs in the region required of thearticle will suffice and it is not necessary to choose the colorcomplementary to that region for absorption purposes based upon achromatic circle.

Several spectrum were carried out on different kinds and colors ofcommercial colorants. In particular, the spectrum focused on the primarycolors and the colors near to red or that contained red. Some spectrumwere available from prior laboratory experimentation and other spectrumwere available from the producers of the colorants. Of the spectrumanalysis performed, all of the spectrum were carried out with a PerkinElmer UV/VS spectrometer Lamda 2, with a scanning rate of 30 nm/minutefrom 250 nm to 780 nm. FIGS. 8A, 8B and 8C show spectrum for variousyellow, red, and blue colorants, respectively. The spectrum are notnormalized, as the interest here was to understand whether or not theregion of absorption of the color was in the visible spectrum.

The comparison between the measurements performed with the SEM and theabsorption spectrum of the primary colors available has led to anexplanation why the red color seems to be the best color to cover thehaze. At this point, however, one must again understand that the resultsof the SEM give the manufacturer an idea of what are the MXD-6 domaindimensions, but in this approach, the measurements are only anapproximation, since it is essentially impossible to cut the sample in amanner that would provide every domain at its longest diameter. That is,at least some of the domains measured will be slightly smaller than thereal diameter, since there is no way to insure that cutting of thebottle will occur in the exact middle of the domains. This issue hasbeen addressed in detail herein above.

After viewing the spectrum, it is clear that, of the choices providedthus far, red appears to be the best candidate for covering haze, withthe best choice being RENOL® Red 4 available from ColorMatrix Corp.Transparent red samples containing the red colorant were prepared andwrapped around a known bottle of the identical size and shape previouslyprepared. The bottle showed visual haze prior to being wrapped. Uponwrapping the bottle, substantial masking of the haze was observed. Otherbottles were prepared to include various colorants. Of those, visualanalysis showed that bottles including the colorant Tersar Yellow NE1105131 available from Clariant provided substantial masking of haze athigher concentration (4%, final bottle has an orange coloration). Whenviewing its spectrum in FIG. 8A, it can be seen that, unlike all of theother yellow colorants with spectrum provided, the spectrum of theTersar Yellow colorant showed at least some absorption in the regionfrom 500 to 550 nm and even out to about 600 nm. Thus, this colorant wassuitable to mask at least some of the haze (or rather the MXD domain) ofthe bottle. In the same manner, bottles made with about 1 percent RENOL®Blue NE 51050340 available from Clariant also showed some partialmasking of the haze. In its spectrum (FIG. 8C), it can be seen that thisblue can cover a zone of the MXD-6 domains. In particular, the regionstarting from 500 nm can be covered. Not all of the region will bemasked however, and there was still some visual haze noticeable in thebottle. The same behavior can be found in using the colorant Tersar blue40642, also available from Clariant (FIG. 8C).

FIGS. 9A, 9B, 9C, and 9D show spectra for various green, orange, purpleand pink colorants, respectively. Notably, the spectrum in FIG. 9A showsthat adding this particular green colorant will not effectively mask thehaze of the bottle. Production of a green colored 500 ml bottle usingthis green colorant confirmed this, a further demonstration that in theregion between 475 and 575 (the spectrum region which is not covered bythe absorption of this color) there are a large number of MXD-6 domainswith this dimension. It will be understood however, that other greencolorants may adequately and effectively mask the haze of the bottle.Not all green colorants absorb at the same wavelengths and in the sameamounts, and it is entirely possible (as shown below) that other greencolorants may provide adequate masking of the visual haze for variousarticles including bottles.

Bottles made from Blossom orange colorant available from ColorMatrixCorp. showed very good masking of haze, but not total. In fact, uponviewing the spectrum of this color (FIG. 9B), it is possible to observean absorption until a wavelength of about 575 nm, not enough to coverall the MXD-6 domains. Again, however, it is possible that other orangecolorants may not mask the visual haze as well as this particular orangecolorant, or may mask the visual haze even better.

The spectrum (FIG. 9C) of Royal Purple-1 available from ColorMatrixCorp. is seen as one of the best colorants to mask haze of the sample500 ml bottle, although the other purple colorant, Tersar Violet 40058,available from Clairant, also appears to be suitable. The pink spectrum(FIG. 9D) also substantially masks haze in the 450 to 600 nm region.

It should thus be evident that, given the spectrum and the testsconducted above, it has been demonstrated that there is a correlationbetween the dimensions of the MXD-6 domains and the absorptionwavelengths of various light absorbent compositions. Where thewavelengths of the region of absorption substantially cover the range ofdimensions of the MXD-6 domains, substantial masking of the visual hazein the bottle occurs.

Further testing of the present invention included the preparation ofadditional preforms of the type described herein above (PET+0.04%PMDA+5% MXD-6) and production of additional 500 ml bottles therefrom, aswell as the manufacture of other, larger preforms made for the sameconcentrations of minor components and larger, 1.5 L bottles molded fromthese larger preforms. Bottles and preforms were then cut in the mannerearlier described and again analyzed at magnification of 5000×. Thistime, the longest direction in both the vertical and horizontaltransverse planes were analyzed. It will be appreciated that the longestdimension in the horizontal transverse plane (X-Z plane) will be thesame dimension as the radial (X) axis dimension in the axial plane ofthe article. Similarly, the longest dimension in the vertical transverseplane (Y-Z plane) will be the same dimension as the axial (Y) axisdimension in the axial plane. SEM analysis of the preforms of the 500 mlbottle showed a mean dimension of MXD-6 domains to be around 240(radial) to about 280 (axial), while the preforms of the 1.5 L bottleshowed a mean dimension of the domains to be about 300 in both theradial (X) and axial (Y) direction. In both of these preforms, thedimensions are so low that they are before, not within, the visiblespectrum and therefore, no haze is seen.

However, in the oriented bottles, the mean dimension of the MXD-6domains was about 500 nm and about 540 nm in the radial direction forthe 500 cc and 1.5 L bottles, respectively, and about 1000 nm in theaxial direction for both bottles. Because of the dimensions in the axial(Y) direction were greater than the visible spectrum, one would notexpect to mask any haze or see any haze from that dimension. However, inthe radial (X) direction, the dimensions fall within the visiblespectrum, and therefore, haze is noted in the bottles.

Further testing included the production of yet another bottle having adifferent resin formulation and a different amount of MXD-6. Inparticular, a polymer matrix was made with a polyester (VFR) resincontaining 10% IPA added of PET (COBITER® 80 Polyester Resin of COBARRS.p.A.) for a final formulation of 8.6% IPA. To this resin was added9.3% of MXD-6. A 38 gram preform was extruded from which a 1.5 L bottlewas made by blow molding. SEM analysis was then preformed on both theperform and the bottle from cuts providing dimensions in the radial andthe axial directions. The results showed a mean dimension of the domainsin the preform to be about 330 nm in the radial (X) direction and about320 nm in the axial (Y) direction. Again, this was well below thevisible spectrum.

For the 1.5 L bottle, the mean dimension of the domains was about 620 nmin the radial (X) direction and about 900 nm in the axial (Y) direction.More importantly, it was found that the range of dimensions were fromabout 490 nm to about 750 nm in the radial direction and from about 660nm to about 1140 nm in the axial direction. Thus, some of the dimensionsin both directions fall within the visible spectrum.

With an aim towards understanding the prior experimental data obtained,some films with different amounts of RENOL® Red-4 colorant fromColorMatrix Corp. were prepared. The experimental data obtained showedan absorbance of this colorant in essentially the same region of theMXD6 domains radial dimension distribution of the 0.5 L bottle. Sampleswere made of cast films with thickness of about 200 microns on a Bausanodouble screw extruder with PET (COBITER® 80 Polyester Resin of COBARRS.p.A.) resin adding different amount of RENOL® Red-4 at 0.05%, 0.1%,0.2%, 0.25%, and 0.5% of weight. The blend was obtained by dry blendingthe right amount of colorant in 2.5 kg of PET for each test in a steelcontainer under essentially standard conditions of temperature, pressureand screw speed.

The obtained films were then placed on the 0.5 L bottle first, and thenon the other bottles, to understand if the colorant is able to maskhaze, and in this case, to find the minimum amount of color required.The realized film and each film's capability to cover haze aresummarized in the Table I below. Since visual haze can be a subjectiveinterpretation of the eye sight of the beholder, the capability of coverhaze was analyzed by asking different people to see through the bottlecovered by the different cast films with different amount of colorantand report whether they can visualize any haze.

TABLE I TESTING OF INDIVIDUALS FOR PRESENCE OF VISUAL HAZE SubstantiallyCovered Haze? (Agreement of All) Color Concentration 0.5 L, 1.5 L, 1.5L, % (RENOL ® Red) 5% MXD 5% MXD 9.3% MXD 0.05 No No No 0.1 No No No0.2* No No No 0.25 Yes — No 0.5 Yes Yes — *obtained by using two 0.1%films — different interpretations (inconclusive)

The above experiment shows that, while the red color is able to coverthe haze somewhat, even at 0.5%, the minimum concentration of RENOL® Redto substantially mask the haze for the 0.5 L bottle was 0.25%, while the1.5 L bottle required a higher concentration, about 0.5%. For the 9.3%MXD bottle, the haze did not disappear when the red colorant was used.It is believed, based upon the spectrum, that significant dimensionswere present outside the region at which the RENOL® Red could adequatelyabsorb light. Consequently, haze remained.

To confirm this theory, films of different concentrations were madecontaining a blue colorant, namely Tersar blue 37843 from Clariant. Uponviewing its spectrum, it can be seen that the light is absorbed fromabout 490 nm up to about 700 nm, or very close to the end of the visiblespectrum. Then, visual tests were conducted with several individuals.The results of the testing are shown in Table II below, wherein it isclear that the use of 0.5 percent of the blue colorant effectivelymasked the visual haze in the bottle.

TABLE II TESTING OF INDIVIDUALS FOR PRESENCE OF VISUAL HAZE ColorConcentration Substantially Covered Haze? % (Tersar Blue 37843) 1.5 L,9.3% MXD 0.05 No 0.1 No 0.25 — 0.5 Yes — different interpretations(inconclusive)

In addition to the above, the physical haze of the bottles was measured.In each instance, whether the bottle was without colorant or withcolorant, there was still a significant physical haze present. In atleast one instance, it appears that physical haze was reduced using theRENOL® Red at 0.25% concentration, but still significantly present inthe bottle.

Further experimentation has found that visual haze is a function of thetotal number of domains having dimensions between about 400 and about700 nanometers that lie in the path of light shining on the article orbottle. Therefore, thickness of the wall plays a role in determining thevisual haze. A thin wall will have less visual haze than its thickercounterpart, even if each wall contains the same number of domains atits surface. The amount of light absorbed must therefore take intoaccount the thickness of the wall.

Accordingly, experiments were performed to determine what amount oflight needed to be absorbed at each wavelength in the visible spectrumto start to make the visual haze recede for various sample bottles usingvarious colorants. First however, the amount of visual haze attributedto a domain was determined by making a stretched bottle wall from ablend of PET and MXD6, determining the frequency of the domains per unitarea, exposing the wall to a very narrow width of light, increasing thelight intensity and measuring the change in luminance required to make awritten word go from readable to hazy.

The wall of the container was prepared from a 52.5 gram preformmanufactured on an Arburg 420c, 110 ton unicavity machine. The preformscontained about 4 and about 6 percent by weight MXD6 Grade 6007 fromMitsubishi Gas Chemical and about 96 and about 94 percent by weightpolyethylene terephthalate grade CLEARTUF® 8006 from M&G Polymers USA,LLC, Sharon Center, Ohio, respectively. The preforms were blown intostandard round bottom 2 liter bottles. The wall was removed and clampedflat between two black boards with a 66 mm×80 mm opening in the center.

The clamped boards with the sidewall in between them were suspendedperpendicular to the tabletop. A 6000 Watt halogen lamp attached to avariable power source was placed about 14 inches from the wall and about7 inches from the top of the table. The light source was shielded fromthe wall by placing a container over the lamp. The container had a 45 mmhole in the side located about 7 inches from the table top to allow thelight to pass from the source and strike the cut out bottle sidewall.

The hole's 45 mm is slightly smaller than the 50 mm diameter lightfilters available from Andover Corporation, Salem, N.H.

A black paper with a single line of 12 point New Times Roman type wasplaced between the sample and the light source, but 4 inches away fromthe sample. The line of type was facing the sample. The edge of thesheet of paper was aligned with the edge of the hole in the bucket sothat the sheet was perpendicular to the table top, parallel to the blackboard, and on the tangent of cylinder whose diameter is defined by thehole and height running from the bucket hole to the black boards. Thewriting was aligned about 7 inches above the table top aligned with thecenter of the sidewall sample, the center of the hole, and even with thelight source. The line of type was observed through the sidewall sample.As the amount of light on the sample increased, the more distorted theline of type became. The amount of luminance required to distort 4letters from the edge tangent to the defined cylinder was consideredhazy.

Filters obtained from Andover Corp were placed in front of the hole toallow very narrow wavelengths of light to strike the sidewall. Thenarrowest wavelength filters were chosen due to their sharp cutoff of 2nm. The wider wavelength filters have much less defined cutoff rangingover 10 to 20 nm and the amount of visual haze contributed by domains inthe whole region will vary with the intensity of light in the cut off.

The amount of light required to create visual haze was measured asfollows. The filters essentially removed about 96% of the visual light.Thus, the background light was reduced so that the amount of lightpassing through the filter was a significant percentage to cause thevisual haze.

Luminance was measured using an EA30 light meter from Extech InstrumentsCorporation, Waltham, Mass. Light was measured at 2 points. The firstpoint measured the light traveling parallel to the boards and strikingthe table top. This point was directly above the sample. This wasdefined as the top light. The other point measured the light travelingparallel to the table top and striking the sample. The meter was placeddirectly in front of the sample facing the light source. Backgroundlight was defined as the amount of light striking the sample when thelight source is turned off.

The intensity of the filtered source light was increased until the firstfour letters of the typed line started to become hazy by looking intothe light at the type through the sample. This measurement was calledOnset Haze. The intensity was then increased until the first fourletters of the typed line became illegible. This was called Max Haze.Each point represents the average of three to five measurementsdepending upon the deviation between measurements.

This evaluation was done for a 4% and a 6% blend of MXD6 at every 50wavelengths beginning at 500 to 650. The measurement at 450 nm was notused as the Extech's manual notes that the meter does not have a validresponse. The luminance at 400 nm and 700 nm were also not measuredbecause the outer limits of the visible light vary from person toperson. From the data taken from this experiment, the percent of lightscattered per domain per unit thickness of the wall of the samplearticle was determined.

The absorbance raw data was normalized to account for the fact that thedomains were concentrated at a few wavelengths. While the luminance wasincreased, only those wavelengths that correlate to domains werereflected. It is believed that a good approximation to determine howmuch of the luminance was reflected was to reduce the increasedluminance by the number of wavelengths passing through the filter whichwavelengths have domain sizes correlating to them. Once this is done forthe filter bandwidth, the relationships become apparent. In short, thelarger the number of domains, the less light is needed to create theonset of haze.

From the data obtained, it was determined that the absorbent compositionhad to be able to do two things. First, the absorption of light by theabsorbent composition must occur at at least one wavelength correlatedwith the size of a domain. Because the domains are usually a pluralityand spread across the visible spectrum, absorbance at many of thewavelengths is likely required. For instance, it is conceivable that ifall the domains were at 500 nm, then only absorption around 500 nm wouldbe needed. Likewise, if 95% of the domains of a PET/6% MXD6 blend wereat 500 nm, then the majority, if not all the absorption, would need tooccur at 500 nm. Alternatively, absorbing light in the other regions,and not absorbing the light around 500 nm would have a limited impact onthe visual haze.

However, contrary to the above example, it was found that the domainswere scattered throughout the visible spectrum, but with severalwavelength regions having substantially more domains than others.Nevertheless, the absorbent composition does not have to absorb in allregions containing domains, but must absorb enough light throughout thespectrum to prevent the light from scattering. Since more scatteringoccurs in regions with more domains, more absorbance is needed atwavelengths with more domains. It has been determined that the onset ofthe haze begins when the light reaches 60% of the total light strikingthis 15 mil wall. Stated another way, a minimum of 40% of the lightstriking the 15 mil wall must be absorbed at a wavelength to begin tohave an impact on the visual haze contributed by the domain at thatwavelength.

For example, for a 15 mil wall, if 80% of the domains were at 500 nm and20% were at 650 nm, the absorbent composition need only absorb 50% ofthe light at 500 nm which is 40% of the total to start to see an impacton the haze. There would be no impact on visual haze if all the lightwas absorbed at 650 nm for that is only 20% of the total light, theremaining 20% of the light absorption would have to be achieved byabsorbing 25% of the light at 500 nm.

This concept has been demonstrated in the following experiment. MXD66007 was melt blended into polyethylene terephthalate and made into a 16oz. bottles. The bottles contained 3% of a colorant (Sprite Green) withabsorbance and a domain distribution as shown in comparison in FIG. 10.The wall was 15 mils thick. Even though there is only an absorbance of0.07 (15% of the light) between 500 and 550 nm, and there are 27 domainsin that region, there was still strong enough absorbance elsewhere tosubstantially reduce the visual haze of the bottle sample. Since the 27domains are only 16% of the total 166 domains in the visual spectrum(400 to 700 nm), the stronger absorbance elsewhere reduced the haze.When calculating for the total amount of relative light available forreflectance (i.e., not absorbed by the colorant) for the bottle sample,that amount is less than 9.6. Thus, while the bottle has a slight amountof visual haze, the absorbance of the colorant is considered enough tosubstantially cover the dimensions of the domains found in the article.That is, the overall visual haze has been substantially reduced.Variations to further reduce the visual haze could be made by increasingthe amount of or the type of absorbent composition(s), which would, inturn, change the absorbances at those wavelengths between 500 and 550nm. To the extent that all of the other wavelengths are “covered,” anyappreciable change in further masking the visual haze of the article maycome from increasing the absorbance at those wavelengths between 500 and550.

Based upon these studies, it has been determined that the amount oflight absorbed within the visible spectrum by the light absorbentcomposition must be such that the summation of the percent of theincident light reflected (i.e., not absorbed) at a wavelength times thenumber of domains per unit area (i.e., square microns) at thewavelength, and assuming constant intensity of light, must be less than9.6. That is, the light absorbent composition must absorb light in thevisible spectrum such that X is less than 9.6 in the equationX=Σ(L _(i))×(N _(i))where L_(i) is the percent of light available to reflect at a wavelengthi and N_(i) is the number of domains per hundred square microns (10⁸nm²) at wavelength i, and where i ranges from 400 nm to 700 nm (i.e.,the visible spectrum).

The thickness of the article is captured in the absorbance reading takenfor the wall of the article. If the intensity of the light a givenwavelength is not constant, it must be included as noted previouslyabove. If 90% of the light occurs at one wavelength correlating to thesize of one domain, then more absorbance of the total light is needed atthat wavelength.

The number of domains is determined by the SEM. The percent lightabsorbed was obtained by the absorbance spectrum which is a function ofthe thickness of the wall. The fraction of light is the lumens orluminance at that wavelength divided by the total lumens or luminance ofthe visible spectrum. For a light of constant intensity, the number is1/300 because the total intensity is equally distributed across thespectrum of 400-700 nanometers.

Still further confirmation of the amount of light needed to be absorbedby the light absorbent composition is set forth in FIGS. 11 and 12. BothFIGS. 11 and 12 include a representative plot graph depicting the numberof domains present in the article (in this case, a 2 L bottle) at eachnanometer between 400 and 700. It will be appreciated that there are nodomains at certain sizes and more than one domain at other sizes.Notably, however, the domains are fairly well spread out throughout theentire range of 400 nm to 700 nm. Superimposed over each plot graph inFIGS. 11 and 12 are representative graphs of the percent of lightabsorbed at each wavelength between 400 nm and 700 nm for a number ofdifferent colorants in amounts ranging from 0.05% to 0.5% for articlescomprising PET/6% MXD6 (FIG. 11) and PET/8% MXD6 (FIG. 12). Inparticular, there are red and green colorants used in FIG. 11, and redand blue colorants used in FIG. 12.

It is to be understood that these graphs show the percent of lightabsorbed (A_(i)), rather than the percent of light available forreflectance (L_(i)). Thus, the determination of whether the colorantemployed will substantially cover the dimensions of the domains presentin the article can essentially be seen by determining whether or not thelatter graph covers the number of domains present. However, increasingthe percentage of light absorbed will not necessarily make it morelikely the colorant will be able to mask the visual haze of the article.One must determine the X value to determine this. Using both the domainplot graph and the percent of light absorbed graph, X can then bedetermined for each of the colorants employed. The X value based uponthe equation present above for each colorant is provided in Table III.

TABLE III X VALUES FOR COLORANTS USED IN PET/MXD6 BLENDS RENOL ® RENOL ®Green Green Green Tersar Tersar Red 0.05% Red 0.1% 0.1% 0.25% 0.5% Blue0.05% Blue 0.1% 6% MXD 10.602 9.167 9.195 7.493 5.573 8% MXD 9.899 8.1679.953 7.272

These bottles were then evaluated separately and subjectively todetermine whether they reduced or eliminated visual haze. It wasdetermined that neither of the 0.05% RENOL® Reds were sufficient toreduce haze, but that at 0.1% the Reds did start to adequately reducevisual haze. Likewise, the 0.05% Tersar Blue was not sufficient toreduce visual haze, but the 0.1% Tersar Blue was adequate to reduce thevisual haze of the bottle. For the Greens, each green reduced the visualhaze to some extent, with higher amount of colorant providing for abetter visually acceptable product with reduced visual haze. This wastrue even though a notable amount of light was transmitted between about480 nm and 540 nm. However, this green colorant absorbs substantiallyall, if not all, of the other wavelengths where domains are present,including a significant amount of light at about 584 nm, where a largenumber of domains existed. Thus, upon calculation of the X value for thecolorant, it was determined to be well within the limits of X being lessthan 9.6. Experimentation has shown that the commencement of somemasking of haze can be set at X=9.55. Thus, it should be evident that,provided the total amount of relative light not absorbed is less than9.6, at least some of the haze visible to the naked eye of an observerwill be masked.

Thus, it should be evident that the haze problem found in containershaving polyamides and other incompatible fillers added to a polymermatrix, particularly those added to improve the gas barrier strength ofthe container, can be masked (or drastically reduced) adding the rightamount of light absorbent composition. There is a close correlationbetween the dimensions of at least some of the domains in the bottle andabsorption wavelength of the absorbent composition. In fact, theexperimental data carried out demonstrates the possibility that haze canbe visually masked using a specific colorant or a combination ofcolorants, as was analyzed and determined in the 0.5 L bottles havingvisual haze.

Additional study has noted that, if there is no change of MXD6 domaindimensions, even after changing of the size of the bottles, and the samePET matrix is used, changing bottle size (to 1.5 L bottles) has littleeffect on the range of domain dimensions, and therefore, visual haze canbe substantially masked by adding the same colorant, although a higheramount of colorant may be preferred.

However, if the PET matrix is changed, and/or the amount of MXD6concentration is increased in the bottle added in a PET, there is achange in the distribution of dimensions of MXD domains. In that case,it was found that the dimensions increased in size by about 100 nm andtherefore, other light absorbent compositions were required to mask thevisual haze of the bottle. In the instance of a 1.5 L bottle having 9.3%MXD-6, a blue colorant better absorbs light in the range of wavelengthscorrelating to the range of dimensions of the domains in that bottle.

Thus, it should be evident that the concepts and methods of the presentinvention are highly effective in providing transparent articlescomprising blends of thermoplastic polymer and incompatible fillers,preferably having reduced gas permeability, that solve the haze problemassociated with such articles. The visible haze of the bottle may besubstantially masked where light is absorbed at wavelengths that atleast substantially correlate to the range of dimensions found for thedomains present in the article. The invention is particularly suited forbeer beverage bottles, but is not necessarily limited thereto. Theconcepts and method of the present invention can be used separately withother applications, equipment, methods and the like, as well as for themanufacture of other oriented articles.

Based upon the foregoing disclosure, it should now be apparent that theuse of light absorbent compositions can substantially mask the haze of atransparent article when the haze is caused by domains having dimensionswithin the visible spectrum. Thus, the dispersion of an incompatiblefiller and, often, a light absorbent composition, in a thermoplasticpolymer matrix in the production of transparent, preferably oriented,articles such as bottles and the like, as described herein, will carryout one or more of the aspects set forth herein above. It is, therefore,to be understood that any variations evident fall within the scope ofthe claimed invention and thus, the selection of specific componentelements can be determined without departing from the spirit of theinvention herein disclosed and described. In particular, colorantsaccording to the present invention are not necessarily limited to thoseof a dye or a pigment. Moreover, as noted herein above, other polyamidescan be substituted for the MXD6 employed in the examples. Thus, thescope of the invention shall include all modifications and variationsthat may fall within the scope of the attached claims.

We claim:
 1. A colored article having visual haze in the absence of an effective amount of one or more light absorbing compositions at a single continuous portion of the colored article; the colored article comprising a thermoplastic polymer matrix; a plurality of domains in said single continuous portion of the colored article wherein said domains are dispersed in the polymer matrix and encompass at least one incompatible filler; and the effective amount of one or more light absorbing compositions; with said domains each having a dimension in an axial plane of the colored article, wherein the dimensions of at least some of said domains in said axial plane of the colored article fall within a range of from about 400 nm to about 700 nm; and wherein the colored article is of a multi-layer construction; and said effective amount of at least one or more light absorbing compositions absorbs light in a region of the visible spectrum at wavelengths corresponding to at least some of the dimensions of said domains in the range of 400 to 700 so that the visual haze of the colored article as compared to the visual haze that is present in the absence of the effective amount of one or more light absorbing compositions at said single continuous portion is reduced when the colored article is viewed in a line of sight perpendicular to said single continuous portion of the colored article.
 2. The colored article of claim 1, wherein said colored article is an oriented container and wherein the single continuous portion of the colored article is a sidewall of the container.
 3. The colored article of claim 1, wherein said colored article is a plastic bottle and wherein the single continuous portion of the colored article is a sidewall of the bottle.
 4. The colored article of claim 1, wherein the thermoplastic polymer matrix is selected from the group consisting of linear polyesters, branched polyesters, polyamides, polystyrenes, polycarbonates, polyvinylchlorides, polyvinylidene dichlorides, polyacrylamides, polyacrylonitrites, polyvinylacetate, polyvinyl methyl ether, ethylene vinyl acetate copolymer, ethylene methyl acrylate copolymer, low molecular weight polyolefins having 2 to 8 carbon atoms, and copolymers, terpolymers, and blends thereof.
 5. The colored article of claim 1, wherein said thermoplastic polymer matrix is a linear polyester matrix selected from the group consisting of polyethylene terephthalate, polyethylene naphthalate, and polybutylene terephthalate, polytrimethylene terephthalate, polyethylene isophthalate and copolymers, terpolymers, and blends thereof.
 6. The colored article of claim 5, wherein said linear polyester matrix is polyethylene terephthalate or a copolymer thereof.
 7. The colored article of claim 1, wherein said incompatible filler is a polyamide.
 8. The colored article of claim 1, wherein said incompatible filler is poly(m-xylylene adipamide).
 9. The colored article of claim 1, wherein said incompatible filler is a gas barrier strengthening filler.
 10. The colored article of claim 1, wherein the article comprises from about 99.5 to about 50 percent by weight thermoplastic polymer and from about 0.5 to about 50 percent by weight incompatible filler.
 11. The colored article of claim 1, wherein said article comprises from about 99.5 to about 50 percent by weight polyethylene terephthalate and from about 0.5 to about 50 percent by weight poly(m-xylylene adipamide).
 12. The colored article of claim 1, wherein said light absorbent composition is a colorant.
 13. The colored article of claim 5, wherein said incompatible filler is selected from the group consisting of thermoplastic polymers other than polyesters.
 14. The colored article of claim 5, wherein said incompatible filler is a polyamide.
 15. The colored article of claim 6, wherein said incompatible filler is poly(m-xylylene adipamide).
 16. The colored article of claim 1, wherein at least one of the light absorbing compositions is a colorant selected from the group consisting of a red colorant, a yellow colorant and a blue colorant.
 17. The colored article of claim 16, wherein said colored article is an oriented container and wherein the single continuous portion of the colored article is a sidewall of the container.
 18. The colored article of claim 16, wherein said colored article is a plastic bottle and wherein the single continuous portion of the colored article is a sidewall of the bottle.
 19. The colored article of claim 16, wherein said thermoplastic polymer matrix is polyethylene terephthalate or a copolymer thereof.
 20. The colored article of claim 16, wherein said incompatible filler is a polyamide.
 21. The colored article of claim 16, wherein said incompatible filler is poly(m-xylylene adipamide).
 22. The colored article of claim 19, wherein said incompatible filler is a polyamide.
 23. The colored article of claim 19, wherein said incompatible filler is poly(m-xylylene adipamide).
 24. The colored article of claim 1, wherein the colored article further comprises a red colorant, a yellow colorant, and a blue colorant.
 25. The colored article of claim 24, wherein the incompatible filler is selected from the group of thermoplastic polymers other than polyesters.
 26. The colored article of claim 25, wherein the incompatible filler is a polyamide.
 27. The colored article of claim 1, wherein the light absorbing composition absorbs light in the region of 400 to 700 nm.
 28. The colored article of claim 27, wherein the incompatible filler is selected from the group of thermoplastic polymers other than polyesters.
 29. The colored article of claim 28, wherein the incompatible filler is a polyamide.
 30. The colored article of claim 1, wherein the thermoplastic polymer matrix is a polyester and the at least one light absorbing composition is the polyester. 